I'm not a DP owner but have done extensive research in your price range for an eventual leap from my 5th wheel. The one thing I know for sure after A LOT of research is to steer clear of early new emission DPs. 2008-2010ish. I'm sure what will follow are 20 anecdotal experiences of people each with a billion trouble free miles but service bays don't lie. They are filled with rigs having work done on complex systems that didn't exist in DPs built prior to 2007 or that have been fine tuned by 2014ish and later.
After my research I decided I'll likely go pre-emission and high quality as opposed to newer and lower quality. Country Coach, Beaver/Monaco, Travel Supreme all are high on my list. The ones you list are all also very nice.